Fexofenadine and its pharmaceutically acceptable salts are useful as antihistamines as disclosed in U.S. Pat. No. 4,254,129 and U.S. Publication No. 2002-0193603 A1. Fexofenadine hydrochloride is available commercially in a variety of solid dosage forms including immediate-release capsules, immediate-release tablets, and sustained-release tablets. There is no disclosure, however, as to an aqueous suspension formulation of fexofenadine or a zwitterionic dihydrate crystalline form of fexofenadine. Neither is there disclosure regarding any suspension formulation as being particularly suitable for ease of dosing children, or for dosing adults having problems with swallowing capsules and tablets, as the suspension formulation according to the present invention would be.